Primary hepatocellular carcinoma (HCC) represents the most common cancer, especially in young men, in many parts of the world (as in China and in much of Asia and Africa) (reviewed in Tiollais et al., 1985). Its etiology was investigated mostly by epidemiological studies, which revealed that, beyond some minor potential agents such as aflatoxin and sex steriod hormones, hepatitis B virus (HBV) chronic infection could account for a large fraction of liver cancers (Beasley and Hwang, 1984).
HBV DNA has been found to be integrated in the genome of most cases of HCCs studied (Edman et. al., 1980; Brechot et al., 1980; Chakraborty et al., 1980; Chen et al., 1982). Nonetheless the role of those sequences in liver oncogenesis remains unclear.
A single HBV integration in a HCC sample in a short liver cell sequence has been reported recently. The sequence was found to be homologous to steroid receptor genes and to the cellular proto-oncogene c-erbA (Dejean et al., 1986).
Ligand-dependent transcriptional activators, such as steroid or thyroid hormone receptors, have recently been cloned allowing rapid progress in the understanding of their mechanism of action. Nevertheless, there exists a need in the art for the identification of transcripts that may encode for activitational elements, such as nuclear surface receptors, that may play a role in hepatocellular carcinoma. Such findings would aid in identifying corresponding transcripts in susceptible individuals. In addition, identification of transcripts could aid in elucidating the mechanisms by which HCC occurs.